Hot-melt adhesive polyester conjugate fiber

Abstract

To obtain an ultrafine heat-shrinkable conjugate fiber at high productivity, in which a flow-drawing state of a polyester undrawn yarn is realized easily and stably. By drawing undrawn yarn comprising a conjugated polyester polymer and olefin polymer, a flow-drawing process can be easily and stably realized using conventional production facilities; and the heat-shrinkable fiber, a drawn intermediate, and an ultrafine hot-melt adhesive conjugate fiber produced by redrawing the drawn intermediate of the present invention can be obtained with high productivity and excellent runnability. More specifically, the ultrafine hot-melt adhesive conjugate fiber obtained by redrawing can be drawn at a heretofore unseen high drawing magnification, and the fiber structure of the olefin polymer constituting part of the conjugate fiber is markedly developed. The heat-shrinkable fiber and ultrafine hot-melt adhesive conjugate fiber thus obtained can be suitably used in hygiene products and industrial materials by utilizing these features.

The invention claimed is: 
     
       1. A hot-melt adhesive conjugate fiber obtained by drawing an undrawn yarn having a polyester as a first component and an olefin polymer with a melting point lower than the first component, as a second component, the hot-melt adhesive conjugate fiber being characterized in that
 the birefringence of the polyester first component of the conjugate fiber is not more than 0.150, and the birefringence ratio of the first component to the second component (birefringence of the first component/birefringence of the second component) is not more than 3.0. 
 
     
     
       2. The hot-melt adhesive conjugate fiber according to  claim 1 , which is a type of conjugation in which the second component completely covers the fiber surface. 
     
     
       3. The hot-melt adhesive conjugate fiber according to  claim 1 , characterized in that the standard deviation of fiber diameter is not more than 4.0. 
     
     
       4. The hot-melt adhesive conjugate fiber of according to  claim 1 , characterized in that the single yarn fiber strength is not more than 2.0 cN/dtex, and the elongation is not less than 100%. 
     
     
       5. The hot-melt adhesive conjugate fiber according to  claim 1 , characterized in that the mean index of refraction of the polyester first component is not more than 1.600. 
     
     
       6. The hot-melt adhesive conjugate fiber of according to  claim 1 , characterized in that the olefin polymer second component is a high density polyethylene. 
     
     
       7. The hot-melt adhesive conjugate fiber according to  claim 1 , characterized in that the dry heat shrinkage resulting from a heat treatment of 145° C. for 5 minutes is not less than 15%. 
     
     
       8. A hot-melt adhesive conjugate fiber comprising a polyester as a first component and an olefin polymer with a melting point lower than the first component as a second component, the hot-melt adhesive conjugate fiber being characterized in that
 the degree of orientation of the c-axis of a crystalline member of the second component of the hot-melt adhesive conjugate fiber is not less than 90%, and the single yarn fiber strength of the hot-melt adhesive conjugate fiber is not less than 1.7 cN/dtex. 
 
     
     
       9. The hot-melt adhesive conjugate fiber according to  claim 8 , obtained by redrawing a conjugate fiber obtained by drawing an undrawn yarn having a polyester as a first component and an olefin polymer with a melting point lower than the first component, as a second component, the hot-melt adhesive conjugate fiber being characterized in that
 the birefringence of the polyester first component of the conjugate fiber is not more than 0.150, and the birefringence ratio of the first component to the second component (birefringence of the first component/birefringence of the second component) is not more than 3.0. 
 
     
     
       10. The hot-melt adhesive conjugate fiber according to  claim 8 , characterized in that the fineness is not more than 4.0 dtex. 
     
     
       11. The hot-melt adhesive conjugate fiber according to  claim 8 , characterized in that the fiber diameter standard deviation is not more than 4.0. 
     
     
       12. A sheet-shaped fiber assembly obtained by processing the hot-melt adhesive conjugate fiber according to  claim 1 . 
     
     
       13. A sheet-shaped fiber assembly obtained by processing the hot-melt adhesive conjugate fiber according to  claim 8 .